Search results for "Photon beam"
showing 10 items of 21 documents
Preliminary application of thermoluminescence and single aliquot regeneration method for dose reconstruction in soda lime glass
2013
The research described in this paper shows that the use of the single aliquot regeneration (SAR) method for thermoluminescence (TL) measurements applied to soda lime glasses allows to carry out a retrospective dose evaluation. We have followed a fast and efficient sample preparation procedure which permits measurements without powdering and sieving processes. We have analyzed the TL signal of commercial soda lime watch glass irradiated with 6 Mega Volts (MV) LINAC photons, 10 MeV LINAC electrons and 62 MeV protons. After the initial exposure and following TL reading, the samples are successively irradiated with increasing doses of photons. Therefore, for each sample its calibration curve is…
ESR response of phenol compounds for dosimetry of gamma photon beams
2014
Abstract In the present paper we investigate the features of IRGANOX® 1076 phenols as a material for electron spin resonance (ESR) dosimetry. We experimentally analyzed the ESR response of pellets of IRGANOX® 1076 phenols irradiated with 60Co photons. The best experimental parameters (modulation amplitude and microwave power) for dosimetric applications have been obtained. The dependence of ESR signal as function of γ dose is found to be linear in the dose range studied (12–60 Gy) and the lowest measurable dose is found to be of the order of 1 Gy. The signal after irradiation is very stable in the first thirty days. From the point of view of the tissue equivalence, these materials have mass…
A Method for Measurements of the Total 2H(γ,π−)PP Cross Sections at Threshold
1979
In recent years measurements of the total cross section for the reactions 2H(γ,π+ nn) and 2H(γ,π0)2H close to the production threshold were performed1. For the 2H(γ,π−)pp reaction data of similar good quality doesn’t exist. In this paper a method is prescribed and the feasibility for the reaction 2H(γ,π−)pp is demonstrated. Figure 1 shows the principle: The photon beam hits a liquid or high pressured gas target of 2H. π− are created on the deuteron and stopped in the same target cell. The major part of the tt are captured π− are captured by deuterons via the reaction 2H(π−,n)n. The energy is shared equally by the two neutrons (En= 68.2 MeV). One of these monochromatic neutrons is detected b…
Total photoabsorption cross sections forH1,H2, andHe3from 200 to 800 MeV
1996
The total photoabsorption cross sections for $^{1}\mathrm{H}$, $^{2}\mathrm{H}$, and $^{3}\mathrm{He}$ have been measured for incident photon energies ranging from 200 to 800 MeV. The $^{3}\mathrm{He}$ data are the first for this nucleus. By using the large acceptance detector DAPHNE in conjunction with the tagged photon beam facility of the MAMI accelerator in Mainz, cross sections of high precision have been obtained. The results show clearly the changes in the nucleon resonances in going from $^{1}\mathrm{H}$ to $^{3}\mathrm{He}$. In particular, for the ${\mathit{D}}_{13}$ region the behavior for $^{3}\mathrm{He}$ is intermediate between that for $^{1}\mathrm{H}$, $^{2}\mathrm{H}$, and h…
A method for measuring total cross sections of (γ, π−) reactions at threshold
1981
Abstract A new method for detecting low energy negative pions has been investigated. The negative pions are identified via monoenergetic neutrons produced in the reaction π − + D → 2 n and detected by means of a time of flight spectrometer. The feasibility for measuring D ( γ , π − ) cross sections near threshold is demonstrated; an extension to heavier nuclei seems to be possible. Futher the method is well suited for applications together with tagged photon beams.
The FiR 1 photon beam model adjustment according to in-air spectrum measurements with the Mg(Ar) ionization chamber.
2014
Abstract The mixed neutron–photon beam of FiR 1 reactor is used for boron–neutron capture therapy (BNCT) in Finland. A beam model has been defined for patient treatment planning and dosimetric calculations. The neutron beam model has been validated with an activation foil measurements. The photon beam model has not been thoroughly validated against measurements, due to the fact that the beam photon dose rate is low, at most only 2% of the total weighted patient dose at FiR 1. However, improvement of the photon dose detection accuracy is worthwhile, since the beam photon dose is of concern in the beam dosimetry. In this study, we have performed ionization chamber measurements with multiple b…
Photoreactions with tensor-polarized deuterium target at VEPP–3
2011
We give an overview of the activity in studying photoprocesses on a tensor-polarized deuterium target, which is carried out at the VEPP–3 electron storage ring. Recent experimental results on tensor asymmetries in two-body deuteron photodisintegration at the photon energy up to 500 MeV, and in coherent pion photoproduction on deuteron are presented. Plans to upgrade the facility and future experiments are discussed. Further progress is connected with the installation of a tagging system for almost-real photons. This would allow us to extend the measurements of polarization observables in photonuclear reactions on deuteron up to a photon energy of 1.5 GeV and permit to perform double polariz…
Threshold enhancement in η photoproduction from 2H and 4He
2002
The photoproduction of η-mesons from 2H and 4He has been studied for energies close to the production thresholds. The experiments were carried out with the tagged photon beam of the Mainz MAMI accelerator. The η-mesons were detected via their two photon decays with the electromagnetic calorimeter TAPS. Total cross-sections, angular and momentum distributions of the η-mesons have been determined for both reactions. The total cross-sections in the threshold region show a large enhancement over the predictions of a participant-spectator model, indicating significant final-state interaction effects. The results are compared to recent model calculations taking into account nucleon-nucleon and nu…
A compact 4He cryotarget
1998
Abstract A thin walled cell of 8 cm length and 3 cm diameter has been constructed for liquid 4 He to be used as a target in a tagged photon beam. The target and the housing have been optimised to allow for detection of charged particles emitted on both sides of the beam. A reservoir of 3 l liquid He and good thermal insulation permitted refilling cycles of 12 h.
THE BARYON RESONANCE PROGRAM AT MAMI
2010
The Mainz Microtron MAMI is an ideal facility to study the hadron structure with the electromagnetic probe. With the fourth accelerator stage (MAMI-C) which went into operation in 2007 high-intensity polarized electron and photon beams with energies up to 1.5 GeV are delivered to the experiments. Polarized targets and recoil polarimeters in combination with dedicated detectors are available for precision experiments in hadron physics. In this article, an overview over selected recent results on the study of low-lying baryon resonances and future perspectives will be given.